Vibrational dampening arrangement for railroad car retarders

ABSTRACT

This disclosure relates to a frictional gripping type of railroad car retarder having a plurality of vibrational dampening wheel and tire assemblies disposed at selected intervals along the running rails in the car retarder for engaging the flanges of the wheels of the passing railway vehicles thereby dissipating vibrational energy imparted to the wheels via the slip-slide action of the brake shoes to thereby prevent the production of wheel squealing or screeching noises.

United States Patent [191 Delvernois, Jr. et a1.

[ Nov. 4, 1975 VIBRATIONAL DAMPENING ARRANGEMENT FOR RAILROAD CARRETARDERS [75] Inventors: Philip J. Delvernois, Jr.,

Monroeville; Peter M. Noble, Valencia, both of Pa.

[73] Assignee: Westinghouse Air Brake Company,

Swissvale, Pa.

[22] Filed: Nov. 15, 1974 [21] Appl. No.: 523,980

[52] U.S. Cl 104/26 A; 188/62; 238/382 [51] Int. Cl. B61B l/00 [58]Field of Search 104/1 R, 26 R, 26 A;

[56] References Cited UNITED STATES PATENTS 1,927,201 I 9/1933 Bone104/26 A X 2,715,369 8/1955 Doehler 104/26 A 3,811,556 5/1974 Kaiser eta1 198/204 OTHER PUBLICATIONS BN Studies Retarder Noise Abatement,Railway System Controls, November 1972, pp. 14-17, 20.

Primary Examiner-M. Henson Wood, Jr.

Assistant Examiner-Randolph A. Reese Attorney, Agent, or Firm-J. B.Sotak; R. W. Mclntire, Jr.

[57] ABSTRACT This disclosure relates to a frictional gripping type ofrailroad car retarder having a plurality of vibrational dampening wheeland tire assemblies disposed at selected intervals along the runningrails in the car retarder for engaging the flanges of the wheels of thepassing railway vehicles thereby dissipating vibrational energy impartedto the wheels via the slip-slide action of the brake shoes to therebyprevent the production of wheel squealing or screeching noises.

11 Claims, 3 Drawing Figures US. Patent Nov. 4, 1975 VIBRATIONALDAMPENING ARRANGEMENT FOR RAILROAD CAR RETARDERS SUBJECT OF THEINVENTION -This invention relates to a novel noise suppressionarrangement for railway braking apparatus and more particularly to aunique rubber dampening arrangement for removing vibrational energy fromthe wheels of a railway vehicle for preventing wheel screeching soundsfrom being produced by wheel clamping types of railroad car retarders.

BACKGROUND OF THE INVENTION In a gravity type of railroad marshalling orclassification yard, it is conventional practice to employ gripping orclamping types of car retarders at both master and group locations tocontrol the leaving speeds of humped railway cars or vehicles.Additionally, it is also becoming increasingly common to employ a carretarder at the exit end of each of the class tracks in the yard to stopthe oncoming railway cars as they are processed into the respectiveclassification tracks. The car retarders frictionally engage or grip theopposite sides of the car wheels to slow down the moving railway cars asthey pass through the master and group location and to stop the railwayvehicles in the class tracks. On numerous occasions, the frictionalgripping action between the brake shoes and wheels results in extremelyloud and piercing squealing noises to permeate the immediate surroundingarea bordering the yard. The bordering area may include residential,business, industrial, commercial and/or governmental properties and mayconsist of homes, apartments, offices, factories schools, hospitals andthe like. These high pitched screeching sounds not only are irritatingor annoying to residents of the area but also are painful and injuriousto working personnel in the yard. In some cases, a partial or total lossof hearing may result when employees are exposed to the retarder noisesfor extended periods of time. It has been found that longtime exposureto sounds above a given critical level adversely affect workmen orsupervisory personnel who work in the area of the car retarders. Theseacute and detrimental sound waves are produced by the stick-slip orrubbing action which takes place between the sides of the wheel rims ofthe moving car and the engaging surfaces of the brake shoes of theactuated car retarder. In actual operation, it has been found that themost troublesome pitch or frequency range of the retarder generatedsound waves lies between 2,000 to 4,000 hertz. Further, the loudness oramplitude level of the noises may reach a 130 decibels db(A) or more ata distance of 8 feet or less from the car retarder. Otolarynologists,audiologists and other qualified specialists have found that humanbeings experience discomfort and pain when exposed to noise levels of120 db(A) or more and that repeated exposure to such high levels ofnoise can eventually result in hearing losses. Recently there have beennumerous proposals and attempts to eliminate or at least reduce thenoise level in order to comply with the regulations of the OccupationalSafety and Hazard Act and the noise pollution ordinances of the given10- cale. However, each of these previous attempts was eitherprohibitively expensive or mechanically unsound and, therefore, did notmeet with industry-wide acceptance. The proposition of replacing steelbrake shoes with ductile iron appeared plausible but proved uneconomical since ductile iron shoes wear four times as fast as steel.Hence, a railroad car retarder equipped with ductile iron shoes normallyrequires four times as many shoe replacements as an all steel retarder.Obviously, a car retarderfitted with ductile iron shoes needs a greaternumber of adjustments and requires more periods of maintenance than acar retarder equipped with steel shoes. The use oflubricants, such as,oils and mixtures of other unctuous liquids, that are sprayed orotherwise applied to the contacting surfaces of the brake shoes andwheels for eliminating wheel squealing or screeching noises is alsopossessed of several shortcomings. The utilization of lubricants notonly materially decreases the effective braking length of the carretarder but also dramatically increases the initial purchase price aswell as the subsequent maintenance cost of the overall car retarder. Afurther deleterious effect of employing lubricants in combating thenoise pollution problem is the unctuous ground covering in the immediatearea of the car retarder as well as the oil dropping pollution yi causedthroughout the classification yard. A furthermethod in attempting toresolve the noise pollution problem in classification yards has been theerection of sound barriers or walls on the respective sides of therailroad car retarder. In previous types of noise barriers, the use ofporous noise absorption material was unacceptable in that they soonbecome relatively ineffective in suppressing the noise produced by thecar retarder The principal reason for the loss in sound attenuationresides in the fact that the porous material readily becomes cloggedwith foreign matter, such as, dirt, oil, grease, water, ice and thelike, which is common in a classification yard environment. In addition,low density types of noise absorption materials are generallysusceptible to rapid deterioration due to the adverse physical andclimatic conditions which are present in railroad yard milieu. Further,it will be appreciated that the maximum theoretical value of noisereduction or attenuation provided by a barrier structure isapproximately 25 db which in many cases is insufficient to conform withthe noise abatement ordinances in the particular locale and the safetystandards set forth in the Occupational Safety Hazard Act of 1970. Inpresent classification yards and in future proposed yard locations, ithas been found that even at substantial distances, 5,000 feet or more,the noise level that permeates the area beyond the boundary line of theyard is in excess of the maximum permissible amplitude set forth in manyof the local noise abatement ordinances. Thus, there is a vital need forproviding an efficient noise reduction arrangement for effectivelyreducing or eliminating wheel squealing or screeching sounds produced byrailroad car retarders. In addition, there is a requirement forattenuating screeching noises that are produced by the wheels when avehicle traverses a curve, tight gauge or the like in the trackway.

OBJECTS AND SUMMARY OF THE INVENTION Accordingly, it is an object ofthis invention to provide a new and improved vibrational energyabsorbing rotary device arrangement for frictional clamping types ofrailroad car retarders.

Another object of this invention is to provide a unique noise reductionarrangement for railway braking apparatus by disposing-a series ofrubber tires along the running rail for dissipating sound producingenergy imparted to the wheels of railway vehicles.

A further object of this invention is to provide a unique vibrationaldampening arrangement employing a plurality of elastomeric rotarydevices for contacting the wheels of railway vehicles as they pass overa curved railroad track.

Yet another object of this invention is to provide a novel noisesuppressing arrangement utilizing a series of vibration absorbing rollerdevices disposed along the length of a car retarder.

Yet a further object of this invention is to provide an antinoisearrangement for railroad cars employing a rotary wheel and tire assemblyfor removing vibrational energy from the wheels of passing railwayvehicles.

Still another object of this invention is to provide a series of rubbertires which are rotatably supported at selected points along the lengthof a railway car retarder to dampen the sound producing vibrationsimparted to the wheels of traversing railway cars.

Still a further object of this invention is to provide in combination asection of railway trackway for guiding and supporting the wheels ofpassing railway vehicles, characterized by a plurality of vibrationalenergy absorbing rotary devices disposed at selected points along thesection of railway trackway and securely fastened to the trackway forcontacting the vehicle wheels for removing vibrational energy from thewheels for preventing the production of wheel squealing noises.

An additional object of this invention is to provide in combination arailroad car retarder having'a plurality of operating units disposedalong the length of a running rail of a trackway, an elongated brakingbar disposed on each side of the running rail and carried by theplurality of operating units, the elongated braking bar including abrake beam and a brake shoe for engaging the wheels of railway vehicles,characterized by a plurality of vibration absorbing rotary devicesdisposed at selected points along the running rail for contacting thevehicle wheels for removing vibrational energy from the wheels forpreventing the production of wheel screeching sounds.

Yet an additional object of this'invention is to provide a novel rubbertire vibration dampening arrangement for railway cars which iseconomical in cost, simple in construction, easy to install and reliablein operation.

In the attainment of the foregoing objects, there is provided a grippingtype of railroad car retarder having a plurality of operating unitslocated along the length of the running rail of a section of track in aclassification yard. Each of the operating units includes a fluidpressure motor and a pair of pivotal levers. Each of the pivotal leverscarries an elongated braking bar which includes a brake beam and brakeshoe movable to a braking position for engaging the sides of the wheelsof railway vehicles traversing the car retarder. The running rail whichextends substantially along the length of the car retarder or which maybe a section of curved trackway or tight gauge is provided with aplurality of vibration absorbing rotary devices located at selectedpoints along its length. Each of the vibration absorbing rotary devicesincludes a wheel and rubber tire assembly. The assembly is rotatablycarried by an axle member which is secured to one of a plurality ofpositions in the web portion of the running rail. Thus, the rubber tiresengage the flanges of the passing wheels of the vehicles and removevibrational energy imparted to the wheels by the slip-slide action ofthe brake shoes so as to prevent the development of wheel squealingorscreeching noises.

Other objects, features and advantages of this invention will becomemore apparent from the following description of the preferredembodiments described with reference to the accompanying drawingsforming a part of this specification, in which: I

FIG. 1 is a fragmentary top plan view of a track section in, forexample, a hump type of railroad freight car classification yard,utilizing a squeeze or gripping type of car retarder for controlling thespeeds of moving railway vehicles and including a plurality of vibrationabsorbing rotary devices selectively located along the length of therunning rail for reducing the production of wheel squealing noises.

FIG. 2 is an enlarged sectional view taken along the lines II-II of FIG.1.

FIG. 3 is a greatly enlarged fragmentary prospective view, partly insection, of one of the vibrational absorbing rotary devices utilized inthe railway braking apparatus of FIG. 1.

Referring now to the drawings and in particular to FIGS. 1 and 2 thereis shown a railroad car retarder generally characterized by numeral 1.In hump or gravity types of classification yards, it is desirable tosort and classify the freight cars or vehicles of an incoming train intoother trains in accordance with their contents "and/or their nextdestination. The railway cars of the incoming trains are pushed over ahump or incline so that the force of gravity moves the cars to theappropriate location in the selected class track. However, variousparameters, such as, car weight, rolling resistance, wind velocity andthe like, cause each of the free rolling cars to travel down thetrackway at a different speed. In order to control the speed of themoving cars in accordance with their rollability and the distance-to-go,it is common practice to provide suitable braking apparatus at the humpand group track locations in the classification yard. Generally, thebraking apparatus takes the form of the squeeze or gripping type of carretarder which has braking bars that are movable into and out ofengagement with the wheels of passing railway cars for controlling thespeed thereof. In group and hump applications, it is common practice toemploy a-dual track car retarder in order to ensure that sufficientbraking effort is exerted on the wheels of the cars as they pass throughthe retarder. 1

As shown in FIG. 1, the dual track car retarder l includes a pluralityof suitable operating units OU appropriately disposed along each rail ofa section of trackway. Each of the operating units OU is substantiallyidentical, and accordingly, a description of one will suffice for all ofthe operating units. As best shown in FIG. 2, a typical operating unitOU consists of an upper lever 3 and a lower lever 4. The levers 3 and 4are operated by a fluid actuated motor M which causes pivotal movementabout the common fulcrum point or pin 5. It will be seen that the freeend of the upper pivotal lever 3 is also pivotally connected to thepneumatic cylinder member 6 of motor M while the free end of the lowerpivotal lever 4 is also pivotally connected to the reciprocal pistonmember 7 of motor M. It will be noted that the upper lever 3 carries anelongated outer braking bar 8 while the lower lever 4 carries anelongated inner braking bar 9. As shown in FIG. 1, the braking bars 8and 9 extend parallel to the track rails and are adapted to be movedrelative to the trackrails into braking and nonbraking positions. Thebraking bars 8 include brake beams 10 whichrare bolted to the uppersurface of levers 3 while the braking bars 9 include brake beams 11which are bolted to the upper surface of levers 4. The braking bars 8include the elongated outer replaceable brake shoes 12 which are boltedto the brake beams 10, and the braking bars 9 include the elongatedinner replaceable brake shoes 13 which are bolted to the brake beams 9.Thus, the pivotal movement of the levers 3 and 4 about the commonfulcrum point causes the braking bars8 and 9 to move toward and awayfrom each other as the fluid motors M are energized and deeenergizedviaconduits 14 and 15 which are connected toa suitable source of fluidpressure (not shown). Hence, upon application of fluid pressure viaconduits l4 and 15 to fluid'actuatin'g motors M, the braking bars 8 and9 undergo an elevating and closing movement so that the brake shoes 12and 13 frictionally engage the sides of wheel W of a traversing railwayvehicle, as shown in FIG. 2. Conversely, upon the venting of the airfrom the actuating motors M to atmosphere via conduits l4 and l5,"theforce of gravity with the'assistance of return springs S operating onlevers 3 and 4 acts to lower and open the braking bars 8 and 9 to theirnormal nonbrakingposition. Accordingly, when a railway car or cut ofcars moves through the retarder, the closing and opening of the brakingbars allows for the speed of the traversing car or cars to be controlledin accordance with its ultimate destination in a class track.

A common occurrence in conventional squeeze or grip types of railroadcar retarders is the production or development of large amplitudevibrations in the vehicle wheels and braking bars when the retarderremains closed for a given period of time. These vibrations imparted tothe wheels build up and result in a very loud and high pitched squealingor screeching noise to be produced by the retarder. That is, thestick-slip mechanism or the rubbing-grating action which takes placebetween the surfaces of the brake shoes and the sides of the vehiclewheels produces sufficient sound generating energy over a period of timeto cause wheel squeal. Thus, the sound producing energy 'should beprevented from building up to the point where the retarder is capable ofdeveloping wheel screeching sounds. In order to abate this noiseproblem, it has been found to be desirous and advantageous to reduce ordampen out the sound producing energy by employing a vibration absorbingarrangement in combination with the railroad car retarder. The noisereductionor elimination is accomplished by constructing the running railwithin the confines of the retarder of an appropriate sound absorbingmaterial. It will be appreciated that the entrance rail sections and 21,namely, the lefthand rails as viewed in FIG. 1 of the drawings, arestandard steel rails, such as, 90 lb. rails. As shown, the rails 20 and21 are fastened to the ends of running rails 22 and 23, respectively, inthe usual manner by means of rail joints 24 and 25. The running rails 22and 23 exwheels to begin to vibrate due to the slip-slide brakingaction. In previous retarder operations, this impetuous force orimparted vibrational energy of the wheels resulted in the generation ofvery high pitched squealing or screeching noises. In the presentinstance, the wheel squealing noises are circumvented by employing avibrational energy dampening or absorbing arrangement in combinationwith the car retarders. As shown, the novel noise suppressingarrangement includes a plurality of a series of vibration absorbingrotary devices 30 suitably located at selected points along the lengthof both of the running rails 22 and 23. In viewing FIGS. 2 and- 3, itwill be observed that each of the rotary devices 30 includes a wheel andtire assembly rotatably mounted on an axleor shaft 31. The wheel andtire assembly includes an outer solid, semipneumatic or pneumatic rubbertire 32'and inner metallic rim or mounting wheel 33. The rim 33 isjournaled to the outer end of the pivotal shaft 31 which is located onthe inner sides of the running rails 22 and 23. The free end of the axleis slightly reduced and passes through a selected one of a plurality ofcontiguous holes or aperatures 34a, 34b or 340 located in the webportion of the running rails. As shown in FIG. 3, the reduced portion isthreaded and is located in the center aperature 34b so that the assemblymay be vertically adjustable or raised when the tread of the tire 32becomes worn after a period of usage. Normally, a new or replacementwheel and tire assembly is located in the lowest slot 340 and is raisedin steps from slot 34c to slot 34b and, in turn, from slot 34b to slot34a as tire wear occurs. It will be seen that the shoulder portion 35 isdrawn against the inner side of the web portion of rail 20 by a nut 36and washer 37 which fit onto the threads of the reduced portion andwhich hold the entire assembly in secure relationship to the top of therail head. It will be appreciated that as the humped vehicle enters thecar retarder, the slipslide action between the wheels W and brake shoes10 and 11 causes vibrational energy to begin to build up in the wheelstraversing the running rails. However, before the amplitude of thevibrational forces is sufficient to cause wheel squealing noises, theflanges of the wheels will contact the tread of the rubber tires 32.Therubber tires provide an energy dampening or absorbing effect on thepassing wheels so that the vibrational forces are removed and dissipatedby the mechanism friction and viscosity of the elastomer tire and wheelassembly. Thus, energy is removed from the wheels of the passing cars bythe first set of vibration absorbing wheel and tire assemblies of thecar retarder 1. It will be appreciated that the engagement of the carwheel flanges with the tire causes the contacted wheel and tireassemblies to rotate so that the amount of abrasive frictional wear isminimized. It will'be noted that the diameter of the wheel and tireassemblies will determine the length of arcuate contact between theflanges and the rubber tire and, in turn, the angular rotation of therubber tires. Thus, the vibration dampening or absorbing effectcontinues through the arcuate contact of the flanges with the rubbertires. As the vehicle wheels W disengage the rubber tires 32,vibrational energy is again imparted to the wheels W due to their soleengagement with the running rails and the closed brake shoes 12 and 13.It will be appreciated that the distance between the first pair of wheeland tire assemblies 30 and the second pair of wheel and tire assemblies30 is chosen to be less than that required to have the vibrational forcebuilt up to the point where wheel squealing will occur. Thus, thevehicle wheels will contact the periphery of the rubber tires of thesecond pair of wheel and tire assemblies before any wheel screechingnoises occur so that the impressed vibrational forces are again absorbedand dissipated by the dampening action of a second pair of vibrationabsorbing rotary devices. Similarly, when the passing wheels disengagethe second wheel and tire assemblies 30, vibrational energy is againimparted to the wheels W but the wheels will engage the third pair ofwheel and tire assemblies 30 before the build up is capable of causingthe production of wheel squealing noises. The energy build up andvibrational dampening is repeated as the wheels pass from the third pairof wheel and tire assemblies to the fourth pair of wheel and tireassemblies, etc. until the wheels emerge from the car retarder and exitonto the stack rails 26 and 27. That is, the vibrational forcesassimilated by the vehicle wheels are repeatedly dampened and dissipatedby the series of vibrational absorbing wheel and tire assemblies 30located along the length of the car retarder 1 so that wheel screechingsounds are prevented from being produced by the slipslide action whichtakes place between the sides of the car wheels W and the surfaces ofthe brake shoes 12 and 13. Accordingly, the plurality of vibrationalabsorbing rotary devices 30 efficiently and effectively prevents the.production of irritating and injurious wheel squealing noises whichwould normally be generated by car retarders in railroad classificationyards.

It will be appreciated that various changes, alterations andmodifications may be made in the embodiment of the presently describedarrangement without departing from the spirit and scope of the subjectinvention. For example, the size of the wheel and tire may be increasedor decreased to vary the contact time between the flanges of the vehiclewheel and the tire 30 to remove a more or a less amount of vibrationalenergy from the vehicle wheels. Similarly, the distance between theadjacent pair of the wheel and tire assemblies may be changed if alesser amount of noncontact time is required to prevent wheel squealingnoises or if a greater amount of contact time is necessary to stop theoccurrence of wheel screeching sounds. It is understood that the rubbertire 32 may be replaced by other suitable elastic material orvibrational dampening material such as, plastic and the like. Inaddition, the wheel and tire assemblies may obviously be arranged instaggered relationship, and the number of wheel and tire assemblies perretarder may be varied in accordance with the particular need of eachspecific installation. It is also understood that the wheel and tireassemblies may be used on curved track sections or where a tight gaugeoccurs in the trackway to reduce the production of wheel squealingnoises. Therefore, it is intended that the subject matter contained inthe foregoing description and shown in the accompanying drawings shouldbe interpreted as illustrative and not in a limiting sense.

Having now described the invention what we claimas new and desire tosecure by Letters Patent, is:

1. In combination, a railroad car retarder having a plurality ofoperating units disposed along thelength of a running rail of atrackway, an elongated braking bar disposed on each side of said runningrail and carried by said plurality of said operating units, saidelongated braking bar including a brake beam and a brake shoe forengaging the wheels of railway vehicles, characterized by a plurality ofvibration absorbing rotary devices disposed at selected points along therunning rail for contacting the vehicle wheels for removing vibrationalenergy from the wheels for preventing the production of wheel screechingsounds.

2. The combination, as defined in claim 1, wherein said vibrationabsorbing rotary devices contact the flange of the vehicle wheels.

3. The combination, as defined in claim 1, wherein said vibrationabsorbing rotary devices are elastic tires.

4. The combination, as defined in claim 1, wherein each said vibrationabsorbing rotary device includes a support shaft which is secured to therunning rail.

5. The combination, as defined in claim 1, wherein each of saidvibration absorbing rotary devices includes a rubber tire bolted to theweb portion of the running rail.

6. The combination, as defined in claim 5, wherein said rubber tire isvertically adjustable for compensating for mechanical wear.

7. The combination, as defined in claim 1, wherein said vibrationabsorbing rotary devices include a pneumatic tire.

8. The combination, as defined in claim 1, wherein said vibrationabsorbing rotary device includes a semipneumatic tire.

9. The combination, as defined in claim 1, wherein said vibrationabsorbing rotary devices include a solid rubber tire.

10. The combination, as defined in claim 1, wherein each of saidvibration absorbing rotary devices includes a wheel and tire assemblywhich is adjustably rotatably supported relative to the running rail bya wheel and axle member.

11. In combination, a section of railway trackway for guiding andsupporting the wheels of passing railway vehicles characterized by aplurality of vibrational energy absorbing rotary devices disposed atselected points along the section of railway trackway and securelyfastened to the trackway for contacting the vehicle wheels for removingvibrational energy from the wheels for preventing the production ofwheel squealing noises.

1. In combination, a railroad car retarder having a plurality ofoperating units disposed along the length of a running rail of atrackway, an elongated braking bar disposed on each side of said runningrail and carried by said plurality of said operating units, saidelongated braking bar including a brake beam and a brake shoe forengaging the wheels of railway vehicles, characterized by a plurality ofvibration absorbing rotary devices disposed at selected points along therunning rail for contacting the vehicle wheels for removing vibrationalenergy from the wheels for preventing the production of wheel screechingsounds.
 2. The combination, as defined in claim 1, wherein saidvibration absorbing rotary devices contact the flange of the vehiclewheels.
 3. The combination, as defined in claim 1, wherein saidvibration absorbing rotary devices are elastic tires.
 4. Thecombination, as defined in claim 1, wherein each said vibrationabsorbing rotary device includes a support shaft which is secured to therunning rail.
 5. The combination, as defined in claim 1, wherein each ofsaid vibration absorbing rotary devices includes a rubber tire bolted tothe web portion of the running rail.
 6. The combination, as defined inclaim 5, wherein said rubber tire is vertically adjustable forcompensating for mechanical wear.
 7. The combination, as defined inclaim 1, wherein said vibration absorbing rotary devices include apneumatic tire.
 8. The combination, as defined in claim 1, wherein saidvibration absorbing rotary device includes a semipneumatic tire.
 9. Thecombination, as defined in claim 1, wherein said vibration absorbingrotary devices include a solid rubber tire.
 10. The combination, asdefined in claim 1, wherein each of said vibration absorbing rotarydevices includes a wheel and tire assembly which is adjustably rotatablysupported relative to the running rail by a wheel and axle member. 11.In combination, a section of railway trackway for guiding and supportingthe wheels of passing railway vehicles characterized by a plurality ofvibrational energy absorbing rotary devices disposed at selected pointsalong the section of railway trackway and securely fastEned to thetrackway for contacting the vehicle wheels for removing vibrationalenergy from the wheels for preventing the production of wheel squealingnoises.